DESCRIPTION: (Applicant's Description) This project will form an internationally supported collaborative research resource for many groups working on the problems of thyroid cancer which has followed the Chernobyl accident. It is designed to promote collaboration and avoid competition in the use of limited and very valued resources. The four funding organizations involved in the project are the National Institute of Health of the USA, the European Commission, the World Health Organization and the Sasakawa Memorial Health Foundation of Japan. The basis of the project is a collaborative approach to the collection of the tissue from cases of thyroid cancer in the areas around Chernobyl with simultaneous collection of blood samples and basic clinical information. The project has several aims (a) to ensure that the best possible diagnostic service is given to patients, (b) to provide a diagnosis agreed by internationally recognized pathologists. This diagnosis will be made available to research groups from those countries carrying out molecular biological, therapeutic, epidemiological and other studies. (c) to ensure that specimens of thyroid cancer are properly described and sampled, and that materials are available for appropriate research studies (frozen tissue, fixed tissue sections, extracted DNA/RNA and blood samples, together with relevant information), through a protocol agreed by the research organizations involved. The project will provide a valuable research tool for future researchers interested in the mechanism of radiation tumourigenesis of the thyroid following irradiation.